The present invention relates to a device for conveying particulate material entrained in a stream of gaseous medium, and more particularly to an agricultural ejector. Even more particularly, the present invention relates to an arrangement for rotating the spout of the agricultural ejector. There are already known various constructions of agricultural ejectors which are used in ejecting grain or chaff or similar particulate material entrained in a stream of air. Generally speaking, they include a housing and a spout which is mounted on the housing and has a free end portion which points in a desired direction. The particulate material entrained in the stream of air is advanced from the housing through the spout and out of the free end portion thereof in the desired direction. Such agricultural ejectors may find use with the various agricultural machines, such as threshers, forage harvesters, cutters or the like. The particular dimensions and construction of the housing and of the spout will depend on the type of the machine with which the ejector is used and on the type of particulate material which is to be ejected from the housing.
In many instances, it is necessary to change the direction in which the particulate material is ejected. This may be necessary in order to, for instance, properly load grain, chaff or similar particulate material into a container, or to properly utilize available storage space.
The prior art has already recognized the need for changing the direction in which the spout discharges the particulate material, and has proposed several arrangements for rotatably mounting the spout on the housing. So, for instance, the device disclosed in the U.S. Pat. No. 3,341,929 utilizes a worm gear transmission which includes a worm wheel connected to the spout for shared rotation therewith, and a worm which is supported on a discharge conduit of the housing for rotation about its axis in meshing engagement with the worm wheel. A crank is connected to the worm and is used for manually rotating the worm so as to angularly displace the worm wheel and thereby the spout.
The arrangement of the worm gear transmission on the discharge conduit of the housing and on the spout, respectively, enables the operator of the ejector or of the machine to which it is connected to rotate the spout at least through 180.degree.. However, this device has the drawback that the manually operated crank must be rotated several times even for a relatively small angular displacement of the spout about its axis so that this device is unsuitable for utilization in ejectors in which the direction of discharge of the particulate material must be accomplished rather rapidly and through large angles such as, up to 180.degree.. The need for rotating the spout through 180.degree. rather suddenly may arise, for instance, in forage harvesters in order to switch the discharge of the grain from a full receptacle to an empty one without any significant loss of the grain or interruption in the operation of the harvester. It will be appreciated that the above-discussed device does not lend itself for rapid change in the direction of discharge and thus cannot be used for this or similar applications. Thus, this device does not satisfy the requirements needed for the utilization of this device in high-output forage harvesters and similar devices.
There is also already known a different device of this type in which a spout of an ejector used in a self-propelled forage harvester is mounted on the discharge conduit of the ejector for rotation about its axis. In this device, a rack-and-pinion transmission is utilized, including a gear wheel mounted on the spout for shared rotation therewith, and a toothed rack mounted on the housing or the discharge conduit thereof for displacement longitudinally of itself in meshing engagement with the gear wheel of the spout. A hydraulic cylinder-and-piston unit is used to displace the rack, whereby the spout is rotated about its axis.
When this device is compared with that previously discussed, it can be observed that the rotation of the spout about its axis can be achieved much more rapidly in this device, even if the angular displacement of the spout amounts of 180.degree. or more. On the other hand, however, this conventional device is also disadvantageous in many respects. So, for instance, the transmission has considerable dimensions, thus taking up a considerable amount of space, which may be at premium in some instances, is rather robust and aesthetically unpleasing, and also expensive in terms of material and labor. This is primarily caused by the fact that the gear wheel of this rack-and-pinion transmission is arranged at the outer circumference of the spout which itself has considerable dimensions, particularly a substantial diameter, which necessitates the provision of the gear wheel of an even larger diameter. When the spout is to be rotated through 180.degree. about its axis, the toothed rack and the displaceable member of the cylinder-and-piston unit must be displaced by a distance corresponding to half the circumference of the gear wheel, that is through a rather considerable distance. As a result of this, the drive of this arrangement has many parts which are spaced a substantial distance from the spout, which is a very undesirable situation that may result even in a danger to the operating personnel.